"Identity" -- the bane of the contemporary Left

Historically, identitarian ideology is a product of the failure of the Left. The various forms of identity politics associated with the new social movements coming out of the New Left during the 60s, 70s, and 80s (feminism, black nationalism, gay pride) were themselves a reaction, perhaps understandable, to the miserable failure of working-class identity politics associated with Stalinism coming out of the Old Left during the 30s, 40s, and 50s (socialist and mainstream labor movements). Working-class identity politics  admittedly avant la lettre  was based on a crude, reductionist understanding of politics that urged socialists and union organizers to stay vigilant and keep on the lookout for alien class elements. Any and every form of ideological deviation was thought to be traceable to a bourgeois or petit-bourgeois upbringing. Ones political position was thought to flow automatically and mechanically from ones social position, i.e. from ones background as a member of a given class within capitalist society.